The present invention concerns a procedure for counting the number of objects which stop on a spot, such as persons who arrive to wait for an elevator or equivalent.
The counting of stopping objects, such as persons waiting for an elevator, is generally accomplished by using e.g. various kinds of contact mats or counters based on the interruption of a light beam.
A contact mat is composed of small switches which close when a person steps on the mat. The information derived from the output of the mat as to how many switchs are closed may be indicated, for instance, by a change of resistance. The number of persons standing on the mat is then proportional to the number of switching elements which have been depressed. The drawback associated with contact mats, apart from their poor mechanical durability in constant use, is also the low reliability of the information furnished by them in elevator lobbies where people may pass through. Another problem is the architecturally objectionable appearance of these mats. Furthermore, the mats command such a high price that in large elevator lobbies the additional cost involved is undesirably high.
Counters, operating on the principle of light beam interruption, allow determination of the number of times the beam has been interrupted. Therefore a means of this type often affords sufficient accuracy in those elevator lobbies which can be accessed from one direction only. However, it is a prerequisite of reliable operation that all those persons who interrupt the beam remain in the elevator lobby. A major
2. drawback hampering photocell counters, similarly as with contact mats, is that passers-through cannot be reliably distinguished from those who stay in the elevator lobby.
It is accordingly an object of the present invention to eliminate these drawbacks and to provide a new type of procedure for counting moving objects as they slow down and stop on a spot. The procedure is reliable in service and well suited for use in various kinds of elevator lobbies for counting the number of people stopping to wait for an elevator.